The major cause of death in cancer patients with solid tumours is the recurrence of the cancer after surgery as multiple metastases are non-resectable and/or refractory to any therapy. The majority of these patients are considered to have a terminal cancer disease. As no treatment is available for them, many of these patients die within weeks or a few months after detection of metastatic tumour lesions.
Tumours develop in cancer patients because the immune system fails to detect tumour cells as cells that ought to be destroyed. Tumour cells express autologous tumour antigens in a large proportion of cancer patients. These autologous tumour antigens may elicit a protective anti-tumour immune response. Tumour cells, or tumour cell membranes, have to be internalized by antigen presenting cells in order to induce the development of an anti-tumour immune response. However, the immune system in cancer patients displays “ignorance” toward the tumour antigens that is associated with early development of the tumour in a “stealthy” way, so it is “invisible” to antigen presenting cells (Pardoll D M. Clin. Immunol. 2000; 95:S44-49; and Dunn G P et al. Nat Immunol 2002; 3: 991-8).
In addition, the tumour microenvironment and local cytokine milieu are often suppressive toward immune function and can actively induce immune cell anergy and death (Malmberg K J. Cancer Immunol. Immunother. 2004; 53: 879-92; Lugade A A et al. J. Immunol. 2005; 174: 7516-23). Effective treatment of such metastatic tumour lesions requires two components:                1. Destruction of the lesions that are large enough to be detected visually or by imaging technology, and        2. Induction of a protective anti-tumour immune response against tumour antigens.        
Such an immune response results in immune-mediated detection, regression, and/or destruction of micrometastases which cannot be detected visually and are not detectable by imaging.
Induction of a protective anti-tumour immune response requires uptake of the tumour cells or cell membranes by antigen presenting cells and their transportation to the draining lymph nodes, where the antigen presenting cells process the tumour antigen molecules. The majority of these tumour antigens are specific to the individual patient. The immunogenic tumour antigen peptides are presented by antigen presenting cells in association with class I or class II MHC molecules for the activation of tumour specific CD8+ and CD4+ T cells, respectively. Only after these T cells are activated by the processed and presented tumour antigen peptides, can these lymphocytes proliferate, leave the lymph nodes, circulate in the body, seek and destroy metastatic tumour cells expressing tumour antigens. In addition, though only after they are activated, helper T cells can provide help to B cells for producing antibodies against the tumour antigens. However, since the tumour cells naturally evolve to be “invisible” to antigen presenting cells, the developing tumour metastases are usually ignored by the immune system to the extent that metastasizing tumour cells can proliferate even within lymph nodes. Therefore, eliciting an effective anti-tumour immune response requires effective targeting of tumour cells to antigen presenting cells.
What is needed are compositions and methods to introduce compounds into a tumour, such as by non-surgical or surgical methods, under conditions such that the compound will insert into tumour cell membranes and a naturally occurring antibody will interact with the introduced compound. It is believed that such interaction will induce local inflammation for the regression and/or destruction of the tumour and the targeting tumour cells and/or tumour cell membranes to antigen presenting cells. This process will elicit a protective immune response in the host against tumour cells expressing the tumour antigens in micrometastases that cannot be detected visually or by imaging and therefore cannot be removed by resection.
US 2006/251661 describes methods of administering natural glycolipid compounds to tumour lesions that induce local expression of α-Gal epitopes within the tumour which interact with the natural anti-Gal antibody.
There is therefore a need to provide an improved method of incorporating α-Gal molecules into a tumour in order to activate an anti-Gal mediated immune response against the tumour, there is also a need for novel pharmaceutical compositions that facilitate this method.